One thing that won't happen is a quadrupling of gas turbine power output.
And the railguns will require more power than they do today. (More power=more boom) Same with the lasers and radars.
Again, with the power requirements of modern day railguns and lasers... This is for an AU, not the real world. Maybe they had a breakthrough in power generation and in power requirements for a rail gun and lasers.
Physics are still physics. In order to make a railgun more powerful you need more power. Advances in superconducters etc. will just make it easier to pump more through them, making the problem even worse.
Now diesel engines and gas turbines are mature pieces of technology, there's no wonder breakthroughs waiting down the line. Sure, we keep building them more and more powerful on a ton for ton basis, but their fuel efficiency won't increase more than a few percent at most. So in order to power all those powerhungry systems for any period of time you'll need huuuge bunker spaces, something your design doesn't have.
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